Engineering recipes have been on the Beta Realm for a while now, but they were in horrible disarray. A good percentage actually had WotLK ingredients, which is a sure sign that those no-good goblins had been ingesting dangerous substances. I didn't think it would be useful to anyone to discuss that situation, but the most recent build has improved the recipes greatly.
I've updated our web site with the most recent versions of Engineering recipes. I left some of the old ones because I suspect they'll be back at some point, they look like our self-buff recipes. What I like about these Cata recipes is that some old favorites are coming back. I'm especially tickled about the Elementium Dragonling. I just recently farmed the Arcanite Dragonling, so I'm glad to see combat pets on the table again. There's also new seaforium charges, a new fishing lure, and finally we can make a crossbow and a bow! We're getting some new additions to the line-up as well, such as the Lure Master Tackle Box, an interesting contraption called a Loot-A-Rang and the Goblin Barbecue :) A couple of new non-combat pets are also on the horizon, they're currently trainable from the specialty vendors.
One thing I'm not so excited about is the Electrostatic Condenser and it's spawn: Electrified Ether. This one-two punch means that only Engineers with a gathering skill will be able to acquire the necessary volatile air used in one of their core Engineering parts. Those of us (yes, me too) who don't have a gathering ability on our Engineer are out of luck. I certainly hope this isn't the final word on volatile collection for Engineers, but I haven't seen any gas clouds in my travels.
I'd also like to point out a new guide on our site, the Engineering Power Leveling Guide. This is the first in my planned series of power leveling guides for primary professions. Traditionally we've only had a power leveling guide for Jewelcrafting, so I thought for Cataclysm I would go back and add similar guides for other tradeskills. Right now I'm only taking them to 300 skill, mostly because I didn't bring the mats to get higher than that. But if I have extra time I'll try to bump some of them up to the 350 or 425 range.
One final tidbit - our Engineering, Alchemy, Inscription and Cooking lists have all been updated to the latest Cataclysm build :) I'll be tackling Enchanting, Blacksmithing and Tailoring next.